[Gta04-owner] problems with battery loading

t.munker at gmx.net t.munker at gmx.net
Fri May 27 21:20:03 CEST 2016


Hi,
my guess was that i did some short circuit (maybe with some higher
resistance) so that voltage is brought from VBUS to the charging
detection pin. But since VBUS is used to charge, i don't know. maybe
the cables impedance plays a role and acts as a small capacitor in
combination to some resistances i introduced while soldering the new
connector?

I've measured at the big usb-end of my charging cable and got following
readings:
left: 0 Volt  to shielding
middle two pins: did't care much, something between 0.6 and 0.9 Volt
right: 5,xx Volt

I can't see any suspicious in these measurements.

I am waiting to buy/lent me an hot air gun, before i open up the phone
and maybe try to resolder again.

Is there any way to ensure that not the IC mentioned by Nikolaus
is defect? 
Any other thoughts?

kind regards,
Thomas Munker



Am Fri, 27 May 2016 12:13:54 +0200
schrieb "H. Nikolaus Schaller" <hns at goldelico.com>:

> Hi,
> 
> > Am 26.05.2016 um 23:33 schrieb <t.munker at gmx.net>
> > <t.munker at gmx.net>:
> > 
> > Hi,
> > thanks for your answer so far!
> > I still have some questions:
> > 
> > Am Thu, 26 May 2016 23:07:29 +0200
> > schrieb "H. Nikolaus Schaller" <hns at goldelico.com>:
> > 
> >> Hi,
> >> 
> >>> Am 26.05.2016 um 20:14 schrieb <t.munker at gmx.net>
> >>> <t.munker at gmx.net>:
> >>> 
> >>> Hi,
> >>> i've got some problem with loading my battery.
> >>> 
> >>> Symptoms are:
> >>> When plugging usb line in at the phone, phone wakes up and starts
> >>> loading, if there is power.  
> >> 
> >> Even without the cable connected on the other end?
> > 
> > The phone even wakes up without the other cable end connected. But
> > does not start loading, since there is no power...
> 
> That is really strange. Wake-up means that there is some power
> detected on the VBUS line. But how connecting just a cable with open
> other end can do this is strange.
> 
> > 
> >> 
> >>> Plugging in at the other end of the usb line is not detected (when
> >>> first plugged in at phone, phone wakes up, but can't load since
> >>> there is no power and goes sleeping again)
> >>> After some seconds (mostly) (sometimes even about half an hour) it
> >>> stops loading, even when battery capacity is still critical.  
> >> 
> >> Hm. Looks like broken cable.
> > 
> > Since i used different cables, i would suspect the connector.
> > 
> >> 
> >>> 
> >>> Old openmoko power adapter doesn't seem to work at all.
> >>> 
> >>> To get the phone usable i need to watch it closely, and unplug and
> >>> replug it, if it stops loading.
> >>> 
> >>> 
> >>> Environment:
> >>> I use QTMoko. Since this has some lag until plugging is detected,
> >>> i use neocontrol to view power status.
> >>> I resoldered my usb-port, maybe something went wrong there. But
> >>> right after resoldering it, it was working good and now got slowly
> >>> worse... Also the sd-card got already corrupted at some point, i
> >>> will reinstall next days to exclude a software error
> >>> 
> >>> 
> >>> Where i need help:
> >>> Is there some way to determine why the phone stops loading?  
> >> 
> >> I don't know about tools but latest QtMoko still uses the old 3.7
> >> kernel which does not have a good charger driver. The main problem
> >> is that it simply stops charging as soon as the USB voltage inside
> >> the GTA04 drops below 4.5V. And does not restart unless you unplug
> >> + replug the cable.
> >> 
> >> This may have a reason in a weak cable or weak power supply,
> >> especially with almost empty battery when the charging current
> >> going through the cable (in parallel to operating the GTA04) is
> >> highest. This may be ~800 mA...
> >> 
> >>> 
> >>> When i want to check my usb-port, is this possible with a simple
> >>> ohm-/volt-/ampere-meter? What are the readings that i should
> >>> expect between the usb-pins when connected correctly to the
> >>> board?  
> >> 
> >> A common source of trouble is if the GND or the shield is not
> >> really connected. This may happen during repair. So you should
> >> check if you have 0V on GND
> >> 3.3V on data lines (may be there only for a very short test cycle
> >> so you can't notice) ca. 1V on the ID line
> >> 5V on the VBUS line
> >> 
> >> For charging, the data lines are not used. Therefore having a good
> >> 5V input is most important.
> > 
> > i don't have a clue about the usb-standard, so i describe here what
> > i hopefully understood:
> > When i look at the big connector side of my usb
> > cable (other side connected to the phone), i guess the left of the
> > outer pins should be GND and have 0V (and 0Ohm) to the shielding.
> 
> Yes. Or no. Some cables have 0 Ohm to shielding others don't. But the
> GTA04 should have 0 Ohm between both.
> 
> > The two inner pins are the data lines, of which one should have 3.3V
> > for some micro seconds and the other is the ID Line and should have
> > 1V (both against the GND, and shield).
> 
> Yes.
> 
> > The right outer pin then is the VBUS line and should measure 5V to
> > GND.
> 
> Yes.
> 
> > 
> > Is there something to say about the resistances between the lines on
> > the phone? I want to check if i did some bad connections...
> 
> If you take an ohmmeter (with low voltage!) you can usually see some
> values above kOhms.
> 
> > 
> > I guess i have to measure voltages, while the gta04 is running?
> 
> Yes.
> 
> > If this
> > should be measured while gta04 is off and connected to some power
> > source, how can i measure them (where should i point my measure
> > tip)? 
> 
> Hm. It could also be a broken ESD chip. It has some diodes inside
> which protect against overvoltage but are high resistance if voltages
> are ok.
> 
> If these diodes allow reverse-current, a voltage on some data line
> may rise VBUS to a level that is detected as a charger wakeup event.
> 
> On the other hand it still does not explain why it happens with a
> cable not plugged to a power supply...
> 
> BR,
> Nikolaus
> 
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